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  • DAY48SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor @1:2320/107 to All on Fri Aug 14 07:55:56 2026
    ACUS48 KWNS 140755
    SWOD48
    SPC AC 140754

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0254 AM CDT Fri Aug 14 2026

    Valid 171200Z - 221200Z

    ...DISCUSSION...
    ...Day 4/Mon...

    A cold front is forecast to extend from the Lower OH/TN Valleys
    toward the southern Mid-Atlantic Monday morning. Some severe risk
    could develop ahead of the boundary as it impinges on a seasonally
    moist and unstable airmass. However, vertical shear is expected to
    remain modest (20-30 kt 0-6 km shear). Thunderstorm clusters could
    pose a risk for locally damaging wind gusts, especially if
    sufficient clustering occurs given moderate to strong downstream
    instability. Severe probabilities may be needed in subsequent
    outlooks if a more organized severe risk appears more likely.

    ...Days 5-8/Tue-Fri...

    Low-amplitude westerly flow aloft will strengthen some around Day 5
    or 6/Tue or Wed as a series of upper shortwave troughs move across
    the northern Plains to the Great Lakes and Northeast through Day
    7/Thu. This could result in increase severe potential across
    portions of the Plains, Midwest, and perhaps the Northeast as the
    upper troughs pivot eastward. Given a prior cold frontal passage and
    surface high pressure across the Midwest through at least parts of
    Tuesday, it is uncertain how low-level moisture/thermodynamic
    recovery will evolve ahead of the upper feature. Depending on
    trends, severe probabilities may become necessary in later outlooks.

    ..Leitman.. 08/14/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Aug 15 07:54:28 2026
    ACUS48 KWNS 150754
    SWOD48
    SPC AC 150752

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0252 AM CDT Sat Aug 15 2026

    Valid 181200Z - 231200Z

    ...DISCUSSION...
    ...Day 4/Tue - NE/IA and vicinity...

    An upper trough over the Great Lakes/Midwest will deepen on Tuesday,
    with increasing northwesterly flow aloft overspreading portions of
    the northern/central Plains to the Mid/Upper MS Valley. Rich
    boundary layer moisture will be in place ahead of a south/southeastward-developing surface front. There is some
    uncertainty regarding possible early-day convection of cloud debris
    across parts of the region. However, most guidance suggests a
    corridor of strong instability will develop by afternoon. Supercell
    wind profiles will support organized cells, possibly growing upscale
    with time along the surface front. Initially, a large hail risk
    could transition toward more of a damaging wind risk, particularly
    if upscale growth does occur as storms develop southeast through the
    evening.

    ...Days 5-8...

    Upper trough will deepen across the eastern U.S. and persist into
    the weekend. Meanwhile, an amplified upper ridge will remain in
    place across the western U.S. A surface front will sag south and
    east on Wednesday and Thursday as upper trough deepens and surface
    high pressure builds over the Great Lakes. Some isolated severe risk
    could emerge over the Mid-South/TN valley toward the Eastern
    Seaboard in response, but deep-layer flow will remain weak and
    low-level winds mostly parallel to the surface front, limiting a
    more substantial/organized risk.

    ..Leitman.. 08/15/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Aug 16 07:54:40 2026
    ACUS48 KWNS 160754
    SWOD48
    SPC AC 160752

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0252 AM CDT Sun Aug 16 2026

    Valid 191200Z - 241200Z

    ...DISCUSSION...
    ...Days 4-5/Wed-Thu -- Mid-South to Mid-Atlantic...

    An amplifying upper pattern is expected mid-week into the weekend,
    with troughing developing across the eastern half of the CONUS and
    an upper riding across the western half. As the upper trough digs
    across the eastern U.S., some severe potential could develop across
    the Mid-South into the southern Mid-Atlantic on Days 4-5/Wed-Thu.
    Building surface high pressure across the Great Lakes and stalled
    upper troughing will result in a slowly sagging surface front arcing
    across the region. With a very moist airmass in place, thunderstorms
    are possible, and at least isolated damaging winds could accompany
    this activity. However, potential appears too limited at this time
    for 15 percent probabilities at the time scale.

    ...Days 7-8/Sat-Sun -- Northern/Central Plains...

    Some severe potential could develop across the Plains during the
    weekend on the eastern periphery of the amplified upper ridge.
    Northwesterly flow aloft will remain enhanced across the region as
    southerly low-level flow on the back side of the Great Lakes surface
    high transports rich boundary layer moisture across the region. It
    is uncertain if capping will preclude thunderstorm development, but
    if any shortwave impulses migrate through northwesterly flow aloft,
    some severe risk could develop.

    ..Leitman.. 08/16/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Aug 17 13:45:52 2026
    ACUS48 KWNS 170750
    SWOD48
    SPC AC 170748

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 AM CDT Mon Aug 17 2026

    Valid 201200Z - 251200Z

    ...DISCUSSION...
    An amplified upper pattern will persist during the Day 4-8/Thu-Mon
    period. An upper trough will remain over the eastern U.S. while
    strong upper ridging spreads from the western U.S. toward the Plains
    late in the period. This pattern will result in moderate
    northwestern flow aloft across portions of the Plains into the
    Midwest. Beneath northwesterly flow aloft and on the eastern
    periphery of upper ridging, a seasonally moist airmass will be in
    place from the Mid/Lower MO Valley into the Upper/Middle MS Valley.
    Some severe potential could develop over these areas through the
    period. However, capping may limit this potential, and with no
    notable features fostering focused large-scale ascent, uncertainty
    is too high to include 15 percent severe probabilities at this time.

    ..Leitman.. 08/17/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Aug 18 08:26:20 2026
    ACUS48 KWNS 180826
    SWOD48
    SPC AC 180824

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0324 AM CDT Tue Aug 18 2026

    Valid 211200Z - 261200Z

    ...DISCUSSION...
    For the Fri/D4 to Tue/D8 period, an upper ridge is forecast to
    expand from the Four Corners states into the Southern Plains, with
    northwest flow aloft over the Northern Plains shifting east across
    Midwest and into the Northeast.

    On Fri/D4, scattered storms may occur across the Central Plains and
    Cornbelt, with areas of moisture and instability beneath the 30-40
    kt northwest flow regime favor scattered hail or strong wind gusts. Predictability is low due to the likelihood of ongoing storms or
    convective systems early in the day, which may affect air mass
    quality and effective boundary positioning. However, the NE/KS/IA/MO
    region appears to be the most likely area for an eventual risk area.

    Also on Fri/D4, storms are again expected over parts of the Mid
    Atlantic to Carolinas, where 25 kt southwest flow in the midlevels
    and a surface trough will support scattered storm clusters producing
    locally damaging gusts. Areas of ongoing storms or outflows from the
    previous day's convection may have an impact here as well as far as
    the most favorable zones for additional severe storms.

    There may also be some potential on Sat/D5 to Sun/D6 over parts of
    the Mid Atlantic as cooling aloft with an upper trough moves across
    the area. Timing of this trough will be critical, as will the
    movement of the associated cold front.

    ..Jewell.. 08/18/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Aug 19 08:30:38 2026
    ACUS48 KWNS 190830
    SWOD48
    SPC AC 190828

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0328 AM CDT Wed Aug 19 2026

    Valid 221200Z - 271200Z

    ...DISCUSSION...
    For the Sat/D4 to Wed/D8 period, an upper ridge will persist from
    the Southern Plains into the Southwest, while various shortwave
    troughs affect the northern Plains, Great Lakes, and Northeast. The
    primary trough amplification will occur from the Upper MS
    Valley/Great Lakes on Sat/D4 into the Northeast through Mon/D6, with
    moisture and instability supportive of strong storms generally
    persisting over parts of the Southeast and Mid Atlantic. Shear will
    remain weak over the East on Sat/D4, with areas of storms producing
    strong gusts, perhaps marginal/isolated severe. By Sun/D5, strong
    winds and cooling aloft will move across the Mid Atlantic and
    Northeast, though antecedent precipitation will affect the warm
    sector, as will veering low-level winds. Frontal timing will depend
    on the upper trough speed, and overall predictability is low for
    Sun/D5.

    To the west, daily corridors of thunderstorms are also likely over
    parts of the central to northern Plains, with northwest flow
    strongest on Sat/D4 and weakening into D5/D6. At least marginal
    risk/low probabilities are likely in later outlooks for isolated
    wind/hail.

    ..Jewell.. 08/19/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Aug 20 08:31:18 2026
    ACUS48 KWNS 200830
    SWOD48
    SPC AC 200829

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0329 AM CDT Thu Aug 20 2026

    Valid 231200Z - 281200Z

    ...DISCUSSION...
    An upper trough will move slowly across the Northeast Sun/D4 into
    Mon/D5, with thunderstorms likely ahead of a cold front. This front
    will likely push offshore on Mon/D5 as a surface low ejects
    northward across Quebec. A moist air mass will remain ahead of the
    front across the Mid Atlantic and into New England, though ongoing
    rain and thunderstorms reduce predictability as far as how unstable
    it will become on Sun/D4. Also mitigating overall severe risk
    appears to be relatively modest low-level wind speeds, with 10-20 kt
    at 850 mb. These areas will be monitored for possible low severe
    probabilities in the coming days.

    To the west, low severe probabilities are possible over parts of the
    northern High Plains, as a small but progressive shortwave trough
    moves out of the Northwest and across the northern Rockies atop the
    upper ridge. West to northwest winds across the northern High Plains
    combined with a lee trough and ribbon of 2000 J/kg MUCAPE should
    support at least isolated hail/wind activity, perhaps from eastern
    MT into the Dakotas.

    Additional storm potential, generally low-end, will be possible
    Tue/D6 into Wed/D7 over much of the Midwest to Great Lakes, though predictability is quite low in forecasting the track of the northern
    wave, which may begin phasing with a developing upper low over
    Ontario.

    ..Jewell.. 08/20/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Aug 21 08:56:24 2026
    ACUS48 KWNS 210856
    SWOD48
    SPC AC 210854

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0354 AM CDT Fri Aug 21 2026

    Valid 241200Z - 291200Z

    ...DISCUSSION...
    A mid-level trough will move across the Northeast on Monday and the
    surface front will be mostly offshore, reducing the severe weather
    threat. As this trough departs, ridging will build across the
    Rockies. This will eventually set up a pattern featuring individual
    mid-level shortwave troughs within northwesterly flow from the
    northern Plains to the Midwest. Some severe weather will likely
    occur with mid-level shortwave troughs within this flow, but these
    details likely will not become more clear until the short term.

    Model consensus indicates a stronger mid-level shortwave trough
    traversing the Pacific Northwest on D7/Thursday. This pattern would
    be favorable for some severe weather threat across Montana, but at
    this time, it appears moisture will stay farther east. Therefore, no
    severe weather is anticipated.

    ..Bentley.. 08/21/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Aug 22 07:44:26 2026
    ACUS48 KWNS 220744
    SWOD48
    SPC AC 220742

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0242 AM CDT Sat Aug 22 2026

    Valid 251200Z - 301200Z

    ...DISCUSSION...
    Overall, the long range pattern will feature a ridge centered over
    the southern High Plains which may shift slightly west through the
    period. Some severe weather may occur within the northwesterly flow
    pattern from the northern Plains to the Ohio Valley Tuesday/D4 to
    Thursday/D6, but confidence is not high enough for probabilities at
    this time. There is an emerging signal for a seasonably strong high
    pressure to build into the eastern CONUS and shunt most of the
    richer low-level moisture to the Gulf Coast states. If this occurs,
    a relative lull in severe weather potential would exist from the
    Mid-Atlantic and Northeast to the Upper Midwest into next weekend.

    ..Bentley.. 08/22/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Aug 23 08:41:00 2026
    ACUS48 KWNS 230840
    SWOD48
    SPC AC 230838

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0338 AM CDT Sun Aug 23 2026

    Valid 261200Z - 311200Z

    ...DISCUSSION...
    ...D4/Wednesday to D6/Friday...
    A mid-level trough will amplify across the Great Lakes region while
    the mid-level ridge maintains its amplitude across the Rockies.
    Within this pattern, some severe weather potential may exist as a
    cold front moves from the Great Lakes to the Northeast. However, the
    signal is not that strong and thus, it is unclear if more than an
    isolated threat will exist; but the evolution of this front and the
    instability associated with it will be monitored.

    ...D7/Saturday to D8/Sunday...
    There is still a fair amount of uncertainty with the evolution of
    the pattern by next weekend, but a general trend toward flattening
    of the upper-level ridge is apparent in the deterministic, AI, and
    ensemble guidance next weekend. This includes moderate flow within
    the zonal region across the central/northern Plains and into the
    Upper Midwest. This period will need to be watched closely as strong instability and moderate shear appear to overlap across a relatively
    broad region, which should support diurnal thunderstorm activity
    given the flattening of the ridge. The specific timing/location of
    these threats will depend on evolution of the pattern and the
    embedded shortwave troughs within the flow. However, it is worth
    noting that the EC-AIFS and the AIGFS both have a signal for a more consolidated mid-level shortwave trough moving across the northern
    Plains on Sunday/D8, which has also been consistently shown by the
    EC-AIFS for the past 4 runs. If this trend continues, there may be opportunities for probabilities to be added in later outlooks.

    ..Bentley.. 08/23/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Aug 24 09:01:06 2026
    ACUS48 KWNS 240900
    SWOD48
    SPC AC 240859

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CDT Mon Aug 24 2026

    Valid 271200Z - 011200Z

    ...DISCUSSION...
    A strong mid-level ridge will be centered over the Rockies on
    Thursday with a broad trough centered across the Great Lakes. The
    ridge will break down over the weekend with a more zonal flow with
    embedded shortwave troughs extending from the Northwest to the
    northern Plains and into the Northeast. Beyond this weekend,
    guidance differs on the evolution of the pattern with considerable
    uncertainty.

    ...D7/Sunday to D8/Monday - Northern Plains...
    Guidance continues to consolidate around an unseasonably strong
    mid-level shortwave trough across the northern Plains into the Upper
    Midwest on Sunday and Monday. There is still some spread around the
    timing of this trough and also the degree of destabilization ahead
    of it. However, despite these timing differences, a moderately
    strong signal for an increasing severe weather threat in this period
    appears to be emerging as a trough with a consistent convective
    signal is shown by the ECMWF and GFS and also by the AI-GFS and
    AI-ECMWF. Ensemble guidance shows a flattened ridge with a mid-level
    jet streak across this region during the same timeframe.
    Surprisingly, AI/ML guidance shows very little signal for a severe
    threat across this region. Analysis of individual ensemble members
    suggests this is likely reflective of the uncertainty in timing and
    location of this trough and greater spread among the ensemble
    guidance. Nonetheless, the potential for an organized severe weather
    threat across the northern Plains and/or Upper Midwest late this
    weekend into early next week appears to be increasing. If guidance
    continues to consolidate with decreasing spread about the timing of
    the trough, severe weather probabilities may eventually be needed.

    ..Bentley.. 08/24/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Aug 25 08:30:18 2026
    ACUS48 KWNS 250829
    SWOD48
    SPC AC 250827

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0327 AM CDT Tue Aug 25 2026

    Valid 281200Z - 021200Z

    ...DISCUSSION...
    Severe weather is possible across the northern Plains into the Upper
    Midwest starting Day 4/Friday and continuing through the weekend.
    The specific evolution remains unclear with quite a range of
    ensemble solutions at this time. Nonetheless, expect severe weather
    somewhere within this broad region each day.

    ...Day4/Friday...
    As the upper-level ridge flattens on Friday, lee troughing will
    develop across the northern High Plains. Moderate to strong
    instability is forecast to develop across the western Dakotas ahead
    of this lee trough. Any weak mid-level shortwave trough to provide a
    focus for this threat remains nebulous. Therefore, the location of
    any surface features remains unclear and thus, it is difficult to
    highlight a more specific region with a greater severe weather
    probability at this time.

    ...Day5/Saturday...
    Severe weather may be possible across portions of the Upper Midwest
    on Saturday, but this threat will be somewhat dependent on the
    location and intensity of Day 4 convection.

    ...Day6/Sunday...
    The ECMWF and AI-ECMWF remain relatively consistent showing a trough
    traversing the northwest on Saturday and emerging across the
    northern Plains on Sunday. Meanwhile, the GFS and AI-GFS have
    trended more progressive, and the individual GEFS members show
    substantial spread in the upper-level pattern for Sunday/Day6. The
    relative consistency in timing and location of the upper-level
    trough from the ECMWF build confidence for this solution. However,
    even the ECMWF and AI-ECMWF trended slightly less amplified with
    this trough. Therefore, the combination of large spread in the upper
    pattern from GEFS members and a slightly deamplified trend from the
    ECMWF provide enough uncertainty to avoid adding probabilities at
    this time.

    ..Bentley.. 08/25/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)